Magnetic convergence device for use in an in-line type color cathode ray tube

ABSTRACT

A pair of E-shaped cores are mounted radially in opposite directions on the outer surface of a neck portion of an inline type color cathode ray tube. Each of the E-shaped cores has a center leg and two side legs about which dynamic convergence coils are wound in radial arrangement relative to the neck portion so as to converge electron beams from the cathode ray tubes along the longitudinal direction of the center legs of the respective cores. First and second disc-shaped permanent magnets are rotatably mounted on a cross-piece connecting the one side ends of the respective legs, and provide adjustable static fluxes cooperating with the dynamic convergence flux by travelling through the center and side legs and across the open ends thereof.

United States Patent 1191 Takenaka et al. July 3, 1973 [54] MAGNETICCONVERGENCE DEVICE FOR 3,496,501 2/1970 Harten et al 335/2l2 USE IN ANIN-LINE TYPE COLOR CATHODE RAY TUBE Primary ExaminerGeorge Harris ArrRob tD. Fl L 0 ard Holtz et al. [75] lnventors: Shlgeo Takenaka; SeljlGoshl; Omey fir ynn e n Kazuhlko ltaka, all of Fukaya-shi, Saitama-ken,Japan [57] ABSTRACT A pair of E-shaped cores are mounted radially inoppo- [73] Asslgnee' {okyo l gl f Electric site directions on the outersurface of a neck portion of awasa apan an inline type color cathode raytube. Each of the E- [22] Filed; Mar. 24, 1972 shaped cores has a centerleg and two side legs about which dynamic convergence coils are wound inradial [21] Appl' 237855 arrangement relative to the neck portion so asto converge electron beams from the cathode ray tubes along [52] U.S.C1. 335/212, 313/77 the ngi in l ir ion of the center legs of the re-[51] Int. Cl. H01t 1/00 speetive ore First an econd isc-shaped permanent[58] Field of Search 335/210, 212, 213; m gn s are ro atably mounted ona cross-piece con- 313/75, 76, 77 necting the one side ends of therespective legs, and provide adjustable static fluxes cooperating withthe [56] References Cited dynamic convergence flux by travelling throughthe UNITED STATES PATENTS center and side legs and across the open endsthereof.

3,305,807 2/1967 Ashley et al. 335/210 11 Claims, 8 Drawing Figures 43 a\36G 42; Q9 M 22x32 251112 1250 l23o\ 3 8 33 3410 320 2 Sheets-Sheet 1FIG.

Patented July 3, 1973 FIG. 2

FIG. 3

Patent ed July 3, 1973 '2 Sheets-Sheet 2 Q 9 M m E: II

FIG.

FIG. 7

FIG. 8

MAGNETIC CONVERGENCE DEVICE FOR USE IN AN IN-LINE TYPE COLOR CATHODE RAYTUBE This invention relates to a magnetic convergence device forconverging the multiple electron beams of an in-line type color cathoderay tube and more particularly to a magneticconvergence device having animproved static magnetic convergence means cooperating with a dynamicconvergence means.

An in-line type color cathode ray tube has recently come into use as acolor cathode ray tube. The in-line type. tube generally has threeelectron guns arranged in linear relationship, and the electron beamsemitted from the guns are directed to a fluorescent screen through theneck portion keeping the in-line arrangement of said electron guns.Among these beams, the center beam is usually for a green color and thetwo side beams are respectively for red and blue colors. To provide aclear and proper color picture over the entire area of the fluorescentscreen, it is necessary for the three electron beams convergently toimpinge on a given small area of the fluorescent screen. For thispurpose, a dynamic convergence means and a static convergence meanscooperating therewith are generally provided on the outer surface of theneck portion in connectqon with the red and blue color electron beams.Further, the red and blue color electron beams should be deflected allover the fluorescent screen so as to obtain a good beam convergence, butany of the conventional convergence devices has failed to effect properdeflection.

Accordingly, it is an object of this invention to provide a magneticconvergence device for use in an inline type color cathode ray tubecapable of adjusting the convergence of multiple electron beamsaccurately and uniformly.

i SUMMARY OF THE INVENTION In accordance with this invention, theabovementioned object can be achieved by providing a magneticconvergence device for use in an in-line tupe color cathode ray tubecomprising a pair of E-shaped cores, each of said cores having a centerleg, two side legs and a cross-piece connecting the ends of said centerand said legs; a nonmagnetic frame having a tubular member for mountingsaid E-shaped cores radially in facing relationship on the outer surfaceof the neck portion of said cathode ray tube; dynamic convergence coilswound about said legs for generating a dynamic convergence fluxtherethrough; two disc-shaped permanent magnets for creating anadjustable static flux cooperating with said dynamic convergence flux bytravelling through said legs and across the open ends thereof; andmeans'for rotatably mounting said permanent magnets on said cross-pieceof at least one of said E-shaped cores.

The present invention can be more fully understood from the followingdetailed description when taken in connection with the accompanyingdrawings, in which:

FIG. 1 is a front view of a magnetic convergence device according to anembodiment of this invention;

FIG. 2 is a side view, partly in section, along line 22 of FIG. 1;

FIG. 3 is a schematic front view of the magnetic convergence device ofFIG. 1, presenting the operation thereof;

FIG. 4 shows a modification of the convergence adjusting mechanism ofthedevice of FIG. 1;

FIGS. 5 to 7 show other modifications of the static convergenceadjusting mechanism of the device of FIG. 1; and

FIG. 8 is a fractional schematic front view of another embodiment of theinvention.

Referring to FIGS. 1 and 2 of the accompanying drawings, a mountingframe 10 is made of a nonmagnetic material, preferably a plasticmaterial. The mounting frame 10 has a tubular member 11 fitted aroundthe outer surface of the neck portion 12 of an in-line type colorcathode ray tube. The three electron beams 13, 14 and 15 representingred, green and blue colors of the color cathode ray tube are aligned inline with one another and separated by magnetic shield plates 16 and 17so as to prevent interaction between the magnetic fields applied to therespective electron 13 to 15. The beams, in particular the beams 13 and15, are therefore independently adjustable and their convergence iscontrolled by magnetic assemblies 18 and 19. The assemblies 18 and 19are positioned external to the neck portion 12 of the cathode ray tubeand adjacent to the internal magnetic shield plates 16 and 17. Theassemblies 18 and 19 create a flux for deflecting the respective beams13 and 15. Each assembly, for example, assembly 18 comprises a dynamicelectromagnet 20 and two disc-shaped permanent magnets 21 and 22. Sinceeach assembly is identical in structure, description of the parts of theassembly 18 will suffice and is applicable to those of the otherassembly 19 which are designated by the same numerals having a letter asuffixed thereto.

The dynamic electromaget 20 has an E-shaped iron core prepared by powdermetallurgy and consisting of a center leg 23, two side legs 24 and 25and a crosspiece, the cross-piece being divided into a portion 26connected to the center leg 23 and two other portions 27 and 28connected to the side legs 24 and 25. Further, said cross--piece hasmagnetic gaps formed by nonmagnetic adhesive spacers 29 and 30 disposedin the boundaries of the adjacent ones of the aforesaid three portions26, 27 and 28. Coils 31 and 32 are wound about the side legs 24 and 25to create an alternting flux by alternating current passing therethroughin addition to the static fluxes of permanent magnets 21 and 22.

Each dynamic electromagnet 20 is secured between side shoulders 33longitudinally of the subject magnetic convergence device with theinnermost ends of the side legs 24 and 25 tightly fitted to the insideof the top shoulders 34 so as to prevent the electromagnet 20 fromunduly approaching the neck portion, that is, to allow a presecribedspace therebetween.

The aforementioned shoulders 33 and 34 are formed on the frame 10 so asto support the side legs 24 and 25 and also fit the innermost ends ofthe legs 23 to 25 around the outer surface of the neck portion 12.

Between the dynamic electromagnet 20 and the end wall 36 of the frame 10are provided permanent magnets 21 and 22 respectively supported byrotatable supporting members comprised of rods 39 and 40 and adjustingwheels 41 and 42. The rods 39 and 40 have projections 37 fitted intoperforations 38 provided in the wall 36 of the frame 10. Between theadjusting wheels 41 and 42 and permanent magnets 21 and 22, there arewound compression coil springs 43 and 44 around the rods 39 and 40 topress the permanent magnets 21 and 22 against the crosspie'ce of thedynamic eleetromagnet 20. The permanent magnets 21 and 22 have bores 45rectangular in cross section to allow the passage therethrough of thetop portions of the rods 39 and 4h having a rectangular cross sectionsimilar to that of the bores 45. Thus the permanent magnets 2R and 22are normally pressed against the dynamic electromagnet 20, and, whenrotated by manually turning the adjusting wheels 41 and 22, can adjustthe direction in which there is created a static flux therefrom. Thepermanent magnets 21 and 22 are respectively so positioned as to bridgethe boundaries defined by the central portion 26 of the cross-piece 28with the adjacent portions 2'7 and 28. The height of the side portionsof the frame lltll gradually decreases toward the end wall 36 tofacilitate the manual rotation of adjusting wheels 41 and &2.

There will now be described by reference to FIG. 3 the operation of themagnetic convergence device shown in FIGS. l and 2. When the permanentmagnet 21 generates a flux in the same direction, that is, the samepolarity arrangement NS as the permanent magnet 22 as shown in the leftside of FIG. 3, then the resultant compound flux F mainly passes throughthe paired side legs 24 and 25 by travelling across a space definedbetween their mutually facing open ends, causing the red color electronbeam 13 to be deflected in the direction indicated by the arrow I or II.The deflecting direction I or II of the red color electron beam 113 isdetermined by the directions in which the compound flux F and said beam13 are travelling. For example, when the compound flux F takes a courseshown by the arrow and the red color electron beam 13 is assumed to passfrom the under to the upper surface of the drawing sheet, then said beam13 will be deflected in the direction of the arrow I. And if the beam 13travels conversely from the upper to the under surface thereof, then thebeam 13 will be deflected in the direction of the arrow II.

On the other hand, when the permanent magnets 21 and 22 create fluxes inopposite polarity arrangements, for example, of SN-NS as shown in theright side of FIG. 3, then the resultant compound flux Fa passes throughthe center leg 23a and is thereafter divided into two portions flowingfrom the open end of the center leg 23a to the open ends of the sidelegs 2 1a and 250. Further when the permanent magnets 21 and 22 createfluxes in different opposite polarity arrangements from the previouscase, that is, NS-SN, then the compound flux Fa travels conversely fromthe open ends of the side legs 24a and 25a to the open end of the centerleg 23a. Accordingly, the blue color electron beam is deflected by thecompound flux Fa in the direction shown by the arrow III or IV. Thedeflecting J direction of said beam 15 is determined similarly inaccordance with the directions in which the compound flux Fa and theblue color electron beam l5 are travelling.

The peripheral portions of the adjusting wheels QR and 42 of FIG. 1 areseparated as viewed in the crosswise direction of the magneticconvergence device but overlap each other as viewed in the lengthwisedirection of said device. However as illustrated in FIG. 4, tofacilitate the manual rotation of the wheels 41 and 42, they may be sodisposed as to have the peripheral portions thereof separated as viewedin the crosswise direction of the magnetic convergence device butprevented from overlapping each other as viewed in the lengthwisedirction thereof as in the previous case.

FIGS. 5 to '7 show the modifications of the static convergence adjustingmechanism of the magnetic convergence device of FIG. I. The staticconvergence adjusting mechanism of FIG. 5 comprises a supporting rodfixed to the end wall 36, the free end of the rod 50 rotatablysupporting the permanent magnet 21!) by being received in a bore 51provided therein, and a compression coil spring 52 for resilientlypressing the magnet Zlb against the cross-piece of the electromagnet 20.

The static convergence adjusting mechanism of FIG. 6 comprises acompression coil spring 53 stretched between the end wall 36 andpermanent magnet 21 for resiliently pressing the magnet 21 against thecross-piece of the electromagnet 20 so as to permit the rotation of saidmagnet 2ll.

The static convergence adjusting mechanism of FIG. 7 comprises ahook-shaped leaf spring 54, the curved portion thereof engaging thesurface of the magnet 21 so as to permit its rotation and the straightportion thereof being secured to the end wall 36.

In another embodiment of the invention of FIG. 8, an integrally formedE-shaped core 55 has side legs 56 and 57, a center leg 58 and across-piece 59 connecting the ends of the legs 56 to 58. Dynamic coils60, 61 and 62 are wound about the respective legs 56 to 58. The otherelements of the embodiment of FIG. 8 are operated in the same manner asthose of FIG. 1 and description thereof is omitted.

The foreggoing description relates to the case where the three legs hadsuch lengths as permitted their close abutment against the periphery ofthe neck portion of the color cathode ray tube, with their end facesvaried accordingly.

However, this invention is also applicable even where the center andpaired side legs constituting the E- shaped core have substantially thesame length and cross section.

What we claim is:

II. A magnetic convergence device for use in an inline type colorcathode ray tube comprising:

a pair of E-shpaed cores, each having a center leg, two side legs and across-piece connecting the ends of said center and side legs;

a non-magnetic frame having a tubular member so as to mount said coresradially in facing relationship on the outer surface of the neck portionof said cathode ray tube;

dynamic convergence coils wound about said legs so as to generate adynamic convergence flux therethrough;

at least two disc-shaped permanent magnets for creating an adjustablestatic flux cooperating with said dynamic convergence flux by travelingthrough said legs and across the open ends thereof; and

means for rotatably mounting two of said permanent magnets on thecross-piece of at least one of said E-shaped cores such that saidpermanent magnets are both rotatable relative to said at least one core.

2. A magnetic convergence device as claimed in claim ll wherein each ofsaid E-shaped cores has a cross-piece separated into first, second andthird divisions respectively connected to said center and side legs withfirst and second magnetic gaps provided between the adjacent ones ofsaid divisions; and said permanent magnets are so positioned as tobridge the magnetic gaps.

3. A magnetic convergence device as claimed in claim 1 wherein saidmeans for rotatably supporting the permanent magnets has two supportingmembers, each of which is pivotally mounted on said frame and has anadjusting wheel, a rod member with a rectangular head, each of saidmagnets having a rectangular bore for slidably receiving saidrectangular head, and a spring member for resiliently pressing saidmagnet against said cross-piece.

4. A magnetic convergence device as claimed in claim 3 wherein the firstand second adjusting wheels included in said two supporting members arepositioned at different distances from the end wall of the frame.

5. A magnetic converence device as claimed in claim 4 wherein theperipheral portions of the first and second adjusting wheels overlapeach other as viewed in the lengthwise direction of the convergencedevice.

6. A magnetic convergence device as claimed in claim 4 wherein saidfirst and second adjusting wheels are so disposed as to prevent theirperipheral portions from overlapping each other as viewed in thelengthwise direction of the convergence device.

7. A magnetic convergence device as claimed in claim 1 wherein saidmeans for rotatably supporting the permanent magnets include supportingrods secured to said frame, said magnets having bores for rotatablyreceiving the free end of said supporting rods and spring members forresiliently pressing said magnets against said cross-piece.

8. A magnetic convergence device as claimed in claim 1 wherein saidmeans for rotatably supporting the permanent magnets include springmembers stretched between said frame and permanent magnets forresiliently pressing said magnets against said cross-piece.

9. A magnetic convergence device as claimed in claim 8 wherein saidspring member is a compression coil spring.

10. A magnetic convergence device as claimed in claim 8 wherein saidspring member is a hook-shaped leaf spring, the curved portion thereofengaging the surface of said magnets and the straight portion beingsecured to said frame.

11. A magnetic convergence device as claimed in claim 1 comprising fourdisc-shaped permanent magnets, and wherein said means for rotatablymounting said magnets includes means for rotatably mounting two of saidpermanent magnets on respective crosspieces of each of said E-shapedcores.

1. A magnetic convergence device for use in an in-line type colorcathode ray tube comprising: a pair of E-shpaed cores, each having acenter leg, two side legs and a cross-piece connecting the ends of saidcenter and side legs; a non-magnetic frame having a tubular member so asto mount said cores radially in facing relationship on the outer surfaceof the neck portion of said cathode ray tube; dynamic convergence coilswound about said legs so as to generate a dynamic convergence fluxtherethrough; at least two disc-shaped permanent magnets for creating anadjustable static flux cooperating with said dynamic convergence flux bytraveling through said legs and across the open ends thereof; and meansfor rotatably mounting two of said permanent magnets on the cross-pieceof at least one of said E-shaped cores such that said permanent magnetsare both rotatable relative to said at least one core.
 2. A magneticconvergence device as claimed in claim 1 wherein each of said E-shapedcores has a cross-piece separated into first, second and third divisionsrespectively connected to said center and side legs with first andsecond magnetic gaps provided between the adjacent ones of saiddivisions; and said permanent magnets are so positioned as to bridge themagnetic gaps.
 3. A magnetic convergence device as claimed in claim 1wherein said means for rotatably supporting the permanent magnets hastwo supporting members, each of which is pivotally mounted on said frameand has an adjusting wheel, a rod member with a rectangular head, eachof said magnets having a rectangular bore for slidably receiving saidrectangular head, and a spring member for resiliently pressing saidmagnet against said cross-piece.
 4. A magnetic convergence device asclaimed in claim 3 wherein the first and second adjusting wheelsincluded in said two supporting members are positioned at differentdistances from the end wall of the frame.
 5. A magnetic converencedevice as claimed in claim 4 wherein the peripheral portions of thefirst and second adjusting wheels overlap each other as viewed in thelengthwise direction of the convergence device.
 6. A magneticconvergence device as claimed in claim 4 wherein said first and secondadjusting wheels are so disposed as to prevent their peripheral portionsfrom overlapping each other as viewed in the lengthwise direction of theconvergence device.
 7. A magnetic convergence device as claimed in claim1 wherein said means for rotatably supporting the permanent magnetsinclude supporting rods sEcured to said frame, said magnets having boresfor rotatably receiving the free end of said supporting rods and springmembers for resiliently pressing said magnets against said cross-piece.8. A magnetic convergence device as claimed in claim 1 wherein saidmeans for rotatably supporting the permanent magnets include springmembers stretched between said frame and permanent magnets forresiliently pressing said magnets against said cross-piece.
 9. Amagnetic convergence device as claimed in claim 8 wherein said springmember is a compression coil spring.
 10. A magnetic convergence deviceas claimed in claim 8 wherein said spring member is a hook-shaped leafspring, the curved portion thereof engaging the surface of said magnetsand the straight portion being secured to said frame.
 11. A magneticconvergence device as claimed in claim 1 comprising four disc-shapedpermanent magnets, and wherein said means for rotatably mounting saidmagnets includes means for rotatably mounting two of said permanentmagnets on respective cross-pieces of each of said E-shaped cores.